docs: def start_index(self):
          """Return the 1-based index of the first item on this page."""
          paginator = self.paginator
          # Special case, return zero if no items.
          if paginator.count == 0:
              return 0
          elif self.number == 1:
              return 1
          return (
              (self.number - 2) * paginator.per_page + paginator.first_page + 1)